python - matplotlib barplot, generic way of setting the xticklabels in the middle of the bar

Question

Following code generates a barplot with the xticklabels centered for each bar. However, scaling the x-axis, changing the number of bars or changing the bar width does alter the position of the labels. Is there a generic way of dealing with that behaviour ?

# This code is a hackish way of setting the proper position by trial
# and error.
import matplotlib.pyplot as plt
import numpy as np
y = [1,2,3,4,5]
# adding 0.75 did the trick but only if I add a blank position to `xl`
x = np.arange(0,len(y)) + 0.75
xl = ['', 'apple', 'orange', 'pear', 'mango', 'peach']

fig = plt.figure()
ax = fig.add_subplot(111)
ax.bar(x,y,0.5)
ax.set_xticklabels(xl)
# I cannot change the scaling without changing the position of the tick labels
ax.set_xlim(0,5.5)

The suggested and working solution:

import matplotlib.pyplot as plt
import numpy as np
y = [1,2,3,4,5]
x = np.arange(len(y))
xl = ['apple', 'orange', 'pear', 'mango', 'peach'] 
fig = plt.figure()
ax = fig.add_subplot(111)
ax.bar(x,y,0.5, align='center')
ax.set_xticks(x)
ax.set_xticklabels(xl)

Answer 1

So the problem is that you only call ax.set_xticklabels. This fixes the labels, but the tick positions are still handled by the AutoLocator, which will add/remove ticks upon changing the axis limits.

So you also need to fix the tick positions:

ax.set_xticks(x)
ax.set_xticklabels(xl)

By calling set_xticks the AutoLocator is replaced under the hood with a FixedLocator.

And then you can center the bars to make it look nicer (optional):

ax.bar(x, y, 0.5, align='center')